(This data in this post pertains mainly to three classes: the Lord, the Samurai and the Ninja; and maybe to these classes as well: the Fighter and the Rogue (depending on how you play them).)Quick Summary: If you're using two weapons, try to make sure they come from the same weapon category (mixing Swords and Daggers is a waste of your skill points) and concentrate on skills in the following order: 1. The specific weapon skill; 2. Dual Weapons; 3. Close/Ranged Combat.
Other possible points of note:
1. The Dual Weapons skill affects accuracy both when using two weapons for Close Combat AS WELL AS WHEN USING TWO WEAPONS FOR RANGED COMBAT. Everyone suffers an accuracy penalty when trying to throw items with both hands. Thus, the Ninja may need to spend points on Dual Weapons as well.
2. Martial Arts (fighting unarmed) is NOT affected by Dual Weapons at all. Putting points into Dual Weapons if you plan to fight with your bare hands (or with only one weapon) is a waste.
3. Fighting with a weapon and a shield is NOT affected by Dual Weapons either.
I did a little analysis of accuracy when using two weapons, and it comes up as follows:
If you are using two weapons from the SAME weapon class (ie. a Katana and a Wakizashi, two Daggers, two sets of Shurikens, etc.), the skill that contributes MOST to your accuracy is the specific weapon skill (ie. Swords, Daggers, Throwing, etc.). The skill that contributes the second greatest amount is Dual Weapons. The skill that contributes the least is Close Combat (or Ranged Combat). Thus, you should try to max the specific weapon skill first, Dual Weapons second, and Close/Ranged Combat last of all.
If you are using two weapons from DIFFERENT weapon classes (eg. a Broadsword and a Dagger), the skill that contributes the most to your accuracy is DUAL WEAPONS. After this comes the specific weapon skill of your PRIMARY weapon (in this case, Swords), and is closely followed by the specific weapon skill of your SECONDARY weapon (in this case, Daggers). Again, the skills that contributes the least is Close Combat. Note that if you use weapons from two different weapon classes, you suffer a double penalty: 1. You need to develop more skills; 2. If your skill in one weapon is low, you are less accurate with THE OTHER WEAPON TOO. Thus, if you want to use two weapons, try to use two weapons from the same weapon class.
PS: As before, all data was gathered from the Demo. If I had the full game, I'd be playing, not wasting time like this. x_x